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Haematology > Disorders of Haemostasis (11&12) > Flashcards

Disorders of Haemostasis (11&12) Flashcards

1
Q

Defective homeostasis with abnormal bleeding is caused by:

A
  1. abnormal blood vessels
  2. thrombocytopenia
  3. disordered platelet function
  4. defective blood coagulation
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2
Q

Types of bleeding:

A
  1. vessel wall abnormalities causes low bleeding due to easy bruising and purpura (bleeding into skin and mucus membranes)
  2. the vascular abnormalities causes moderate bleeding due to purpura
  3. the coagulation abnormalities cause severe bleeding as the platelets cannot clot so bleeds in joints and tissues
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3
Q

Vascular bleeding disorders:

A

Inherited disorders:

  1. Hereditary haemorrhagic telangiestasia
  2. Connective tissue disorders
  3. Giant cavernous haemangioma

Characteristics: easy bruising, spontaneous bleeding even when there is no injury

Pathology: abnormality in blood vessel walls as tests come out normal so you do the tests to decide what yuou dont have

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4
Q

Hereditary haemorrhagic telangiestia

A
  • uncommon (1.5 mill)
  • autosomal dominant
  • defects 3 genes but only caused by 1
  • very thin blood vessels
  • symptoms: telangiestases (dilated microvascular swellings), nose/tongue/lips, nosebleeds and GI tract blood loss (20-25%)
  • increases in severity when you’re older but the incidence is decreased - usually manifests in middle-aged adults
  • Treatment: embolisation, laser or transexemic acid
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5
Q

Causes of Acquired Vascular defects:

A 
drug reactions
steroids
infections
old age
trauma
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6
Q

Purpura simplex (acquired vascular defect):

A

common benign disorder

occurs in women at a child bearing age

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7
Q

Serile purpura (acquired vascular):

A

old age
loss of skin elasticity, atrophy and collagen
happens in forearms, like bingo wings

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8
Q

Infection associated purpura (acquired vascular):

A

bacterial

viral (measles)

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9
Q

Causes of Thrombocytopenia:

A
  1. failure of platelet production (anaemia)
  2. increased destruction of platelets as they prematurely breakdown
  3. sequestration in the spleen (carries 90%)
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10
Q

Failure of platelet production:

A
  • the most common cause
  • bone marrow failure (aplastic anaemia or leukaemia)
  • drug or viral toxicity

Diagnosis:

  • clinical history
  • blood film
  • peripheral blood count
  • bone marrow tests
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11
Q

Destruction of premature platelets:

A
  • primary cause is autoantibodies attaching to platelets causing them to breakdown
  • can have two autoimmune idiopathic thrombocytopenia purpura (AITP):
  1. chronic AITP
  2. acute AITP
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12
Q

Chronic AITP:

A
  • common in young women
  • asymptomatic
  • autoantibodies in PM (IgG sensitivity by platelets)
  • destroyed by macrophages in the spleen/ liver
  • platelet lifespan is reduced to a few hours
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13
Q

Autoantibody types in chronic AITP:

A

glycoprotein IIb
IIa
Ib

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14
Q

Acute AITP:

A
  • can lead to chronic
  • in children under 10
  • a viral episode can cause this (like chicken pox or measles)
  • likely that IgG attaches to the viral antigen and absorbed into the platelet surface so that the autoantibodies attack the platelets
  • (platelet count is less that 20 x 10^9 L)
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15
Q

Sequestration:

A
  • spleen contains 30% of all platelets

- this goes up to 90%

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16
Q

Thrombocytopathy:

A
  • disorder of platelet function
  • count is normal
  • inherited is rare
  • acquired is common
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17
Q

Anti-platelet drugs (Acquired disorders of platelet function):

A
  • aspirin
  • irreversibly inactivate COX enzyme
  • prevents production of TXA2
  • inhibits platelet aggregation
  • GI tract begins to bleed
  • extends bleeding time and can cause haemorrhage
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18
Q

Haematological Malignancy (Acquired disorders of platelet function):

A
  • acute myeloid leukaemia
  • any myeloid diseases become myelomas
  • some of these cells stem from platelet production
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19
Q

Diagnosis of disorders:

A
  1. blood count on blood film
  2. bone marrow biopsy
  3. prolonged bleeding time
  4. hereditary defects require further testing
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20
Q

Extra reading on thrombocytopenia:

A
  • bone marrow cells become over stimulated and produce too many platelets
  • TPO (thrombopoietin) triggers production
  • receptor for TPO, Mpl on blood cells were examined
  • identified cells that make TPO on platelets
  • TPO did not act on megakaryocytes but stem cells and precursors to cause the production to go wrong
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21
Q

Defective Coagulation:

A
  • inherited factors
  • acquired factors
  • haemophilia A/B
  • vWF disease
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22
Q

Haemophilia A Facts:

A
  • most common
  • deficiency in factor 8 due to mutations
  • 30-100 million affected
  • X-linked recessive disorder
  • can be spontaneous
  • lots of people given blood transfusions in europe and USA were HIV positive so had acquired the disease
  1. all sons of an affected male will be normal
  2. all daughters are carriers
  3. all males have a defective gene
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23
Q

Haemophilia A clinical features:

A
  • bleeding in joints
  • haemathrosis elbow (swollen)
  • pain in affected areas
  • can be fatal if leads into cranial region
24
Q

Haemophilia A diagnosis:

A
  1. Prolonged APTT
  2. confirmed factor 8 deficiency by assay
  3. detector by DNA analysis
  4. chronic biopsies at 8-10 week in utero
25
Q

Symptoms of Haemophilia A:

A

50-100% factor conc. then no bleeding
25-50% factor conc. then severe bleeding after trauma
5-25% factor conc. then episodes after surgery or trauma
5% factor conc. then severe bleeding after slight trauma
<1% factor conc. then severe bleeding into joints after slight trauma

26
Q

Treatment for Haemophilia A:

A
  1. factor 8 blood transfusion
  2. use DOAVP to mobilise factor 8 from endothelial cells after a minor case
  3. gene therapy
27
Q

Haemophilia B Facts:

A
  • X-linked recessive disorder that causes bleeding
  • deficiency in factor 9 due to mutations
  • 15-20 million effected
  • clinically not detectable from Haem. A
28
Q

Haemophilia B clinical features:

A
  • reoccur-ant joint bleeds
  • haemothrisis elbow (swollen elbows)
  • bruising
  • pain in affected areas
  • can be fatal if in cranial regions
29
Q

Haemophilia B diagnosis:

A
  • APTT prolonged

- confirmed by factor 9 clotting assay

30
Q

Haemophilia B treatment:

A
  • factor 9 replacement by blood transfusions
31
Q

vWF Facts:

A
  • 1 in 100 asymptomatic
  • clinically significant in 1 in 10,000
  • autosomal dominant
  • most are heterozygous
  • vWF is a large protein in plasma
  • promotes platelet adhesion to the damaged endothelial layer
  • carrier of factor 8
32
Q

vWF disease classification:

A
  • type 1 and 3 have a partial reduction or nearly complete absence of vWF
  • type 2 has an abnormal form of vWF and function
33
Q

vWF disease diagnosis:

A
  • prolonged APTT
  • decreased factor 8 clotting activity
  • low levels of vWF
  • unpaired platelet aggregation
34
Q

vWF disease clinical features:

A
  • extent of bleeding variable
  • spontaneous purpura
  • severe haemorrhage following surgery
35
Q

vWF disease Treatment:

A
  • DDAOVP
  • increase factor 8 and vWF with transfusion and replacement (type1 most affected)
  • transexamic acid for mild bleeding
36
Q

Extra reading to prove vWF disease type 2:

A
  • mutant vWF disease mice were able to bind platelets but unable to activate them
  • inhibits clot formation
37
Q

Acquired coagulation disorders:

A
  • more common than inherited
  • usually multifactorial
  • associated with varying assortments of platelet dysfunction and coagulation abnormalities
  • vitamin k deficiency
  • dissemiated (spread) intravascular coagulation
  • leads to infections, trauma and sepsis (excess tissue factor made)
  • coagulation produced and its inhibitors so results in no net production
  • very hard to treat
38
Q

A thrombus:

A

platelets and fibrin form a basis that forms into a blood clot in the arterial or venous ends (increased incidence with age)

39
Q

An embolism:

A

occlusion of vessel by a foreign body (like a blood clot)

40
Q

Thromboembolism:

A

occlusion of vessel by blood clot which has moved from its initial position

41
Q

Risk factors for Thrombosis:

A

differ between venous and arterial

42
Q

Thrombophilia:

A
  • inherited or acquired

- predisposed to thrombosis

43
Q

Virchow’s triad:

A
  1. changes in blood flow
  2. changes in blood constituents
  3. changes within walls of blood vessels
44
Q

Arterial Thrombosis:

A
  • artery + thrombus = rupture of atheroma
    1. stroke
    2. myocardial infarction
45
Q

Stroke:

A
  • disturbance in blood supply to the brain

- thrombotic stroke as thrombus forms around fatty plaques which leads to a block

46
Q

Myocardial Infarction:

A
  • caused by an infarct (death of tissue known as ischemia)
  • obstruction of coronary artery
  • if detected within 12 hours can be treated
47
Q

Risk factors for Myocardial Infarction:

A

age
smoker
diabetes
hypertension

48
Q

Venous Thrombosis (thromboembolism):

A
  • increased systemic coagulability and stasis

- deep vein thrombosis (DVT) in the lower limbs

49
Q

Symptoms of Venous Thrombosis (thromboembolism):

A
  • swelling
  • pain
  • pulmonary embolism (dyspnoea, chest pain and tachpronea)
50
Q
  1. Risk Factors of Venous Thrombosis (thromboembolism):
A
  1. Coagulation abnormality
  • hereditary is factor 5 - Leiden
  • can be acquired
  • increased plasma levels of factor 7, 8, 9 and 11 and of fibrinogen
  • lupus anticoagulant
  • oral contraceptive
  • malignancy
51
Q
  1. Risk Factors of Venous Thrombosis (thromboembolism):
A
  1. Stasis
  • strokes
  • cardiac failure
  • prolonged variability
52
Q
  1. Risk Factors of Venous Thrombosis (thromboembolism):
A
  1. Unknown factors
  • ages
  • obesity
  • sepsis
  • NSAIDs
53
Q

Inherited Thrombophilia (factor 5 Leiden) Facts:

A
  • activated protein c resistance
  • autosomal dominant
  • most common to risk of thrombosis
  • occurs in 5% of caucasians
  • 90% of cases are a single point mutation
  • arg to glu
  • factor 5 is less susceptible to cleavage by protein c
54
Q

Risk factors of Inherited Thrombophilia (factor 5 Leiden):

A
  • venous stasis
  • dissemiated cancer
  • alterations to blood flow like AF
55
Q

Therapy for Inherited Thrombophilia (factor 5 Leiden):

A
  • anticoagulants to prevent thrombosis and stabilise clot like heparin and warfarin
  • thrombolytic agents to dissolve thrombus such as plasminogen activators which convert to plasmin to break down the fibrin clot
56
Q

Meds for Inherited Thrombophilia (factor 5 Leiden):

A
  1. streptokinase that activated free and fibrin bound plasminogen to release plasmin
  2. tissue plasminogen activator (TPA) which has a high affinity for plasmin and causes thrombinolysis

Haematology (5 decks)

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